Flame retardant or flame resistant fabrics are desirable in the textile industry for a variety of applications, and in particular as industrial and military clothing and equipment, including uniforms, tents and shelters. They are also found in a wide range of products in the consumer and medical fields.
There are currently two main ways of rendering fabrics fire retardant or flame resistant. The first is to apply a fire retardant coating or finish onto a fabric substrate. This approach suffers from the drawback that the weight of the fabric is increased, which may not be desirable where the fabric is to be worn in skin contact. Fabrics intended to be worn or carried by workers or soldiers is typically coated with a lighter weight coating to preserve some of the “hand” of the original fabric, but this limits the amount of fire retardancy that can be imparted. Fire retardants can also be incorporated within the fabric by dipping the fabric in a bath of a fluid containing appropriated agents, however, this approach is generally not capable of making highly fire retardant fabrics given the limited amount of material that can be deposited and retained on the surface of the fibers. Moreover, the additive typically is not durable to mechanical abrasion or laundering of the article. Attempts to impart greater durability to fire retardant finishes often yield a fabric which is stiff and lacking the hand required for clothing. The conventional practice is to treat fabrics with both fire retardant coatings and finishes. While it is possible to achieve good fire retardancy, this approach may negatively impact other performance characteristics, such as water repellency, moisture vapor transmission (breathability), tear strength, air permeability, flexibility, and hand and feel of the fabric. In fact, the addition of a coating or finish alone may affect performance attributes, such as breathability, air permeability, and weight. Generally, utilizing flame resistant coatings or finishes makes it more challenging to meet all performance specifications required for a technical fabric.
The second way of achieving a fire resistant fabric is to utilize inherently flame resistant fibers, such as meta-aramide, para-aramide, carbon, and rayon. For example, DuPont's NOMEX® fibers are meta-aramide-based fibers which are marketed as having good resistance to burning. One drawback to this approach is the expense associated with manufacturing and processing these specialty fibers relative to standard fibers, such as nylon-6 and nylon-6,6. Fabrics made from these fibers (e.g., NOMEX®) alone, or as blends, are difficult to process using typical textile materials and equipment. Moreover, additional performance requirements, such as water repellency, infrared reflectance, breathability, weight of fabric, tensile and tearing strength, abrasion resistance, strength and growth, flexibility and soft hand, are challenging to obtain when using inherently flame resistant fabrics. It is also difficult to dye and print these fabrics to proper color requirements. Special chemical auxiliaries and equipment frequently must be employed to process fabrics of inherently flame resistant fibers.
As such, there is a need for flame resistant fibers that are relatively inexpensive to produce. There is further a need for fabrics comprised of flame resistant fibers which are characterized by durable fire retardancy, without the need for heavy fire retardant coatings. There is also a need for fire retardant fibers and fabrics that can be processed (e.g., woven, dyed, printed, calendared, washed, etc.) on conventional textile equipment. It is therefore an object of the invention to provide fibers comprising fire retardant agents that overcome one or more drawbacks of the prior art.